The invention concerns a device for heat treatment of body tissue in accordance with patent claim 1.
Certain conditions of illness with unnatural growth of body tissue are successfully managed by the use of heat treatment. The tissue is heated to such an extent that the tissue dies. Certain types of cancer and hyperplasia in the prostate gland are examples of such conditions of illness. During treatment certain parts of the tissue are to be treated whereas others must or should be protected.
Various devices may be used for the purpose of producing heat. Laser as well as microwave and RF antennas are commonly used. Because the volume of the tissue to be treated varies, as does the heat-absorption quality of both this first-mentioned tissue and adjacent tissue, which is not to be treated, it is appropriate that continuous control takes place during treatment.
It is commonplace that the means of heating comprises some kind of a temperature sensor, which is provided on the heat-producing element to sense the temperature of an adjacent tissue. A drawback of this design is that the temperature sensor lends information that is more pertinent to the temperature of the element than to that of the tissue.
An example of this type of heating device is shown and described in EP 0 370 890. The device comprises a microwave antenna enclosed in a catheter. The antenna is designed to emit electromagnetic energy to the tissue surrounding the antenna. The catheter is also equipped with cooling channels for cooling of the tissue closest to the catheter. There is provided a temperature transducer in the catheter to sense the temperature of the catheter. The temperature sensed therefore does not agree with that of the tissue to be treated.
Another example of this is to be found in U.S. Pat. No. 5,366,490. According to that patent specification, previously known heating devices present multiple drawbacks. The most critical of these drawbacks is that heating takes place in a diffusely defined area or volume. In particular systems comprising a microwave antenna in a catheter, it is specified, lead to great risks and worse treatment outcome because the area of treatment is not narrowly defined.
According to U.S. Pat. No. 5,366,490, it is therefore suggested that the means of treatment is provided in a needle which is advanceable so as to exit a catheter. The catheter and then the needle are controlled very accurately in place with the aid of an ultra sound device, which during the entire treatment continuously monitors the area of treatment. Control of the needle must be very precise since treatment efficiency is locally very high in the vicinity of the needle. The treatment is a surgical one. There are high demands on the person who carries out the treatment and on the surgical equipment required.
It is an objective of the present invention, when it comes to conventional types of heat treatment devices, to provide a device which eliminates the drawbacks of diffusely working heating means that are equipped with temperature sensors. The objective is achieved by the features indicated in claim 1. According to the present invention, registration of relevant temperature data from the body tissue is readily made possible. Treatment made possible through the device according to the invention may take place in an outpatient setting without the requirement of surgical staff and equipment or operation rooms.